This invention relates to the use of compounds as inhibitors of the fatty acid synthase FabH.
The pathway for the biosynthesis of saturated fatty acids is very similar in prokaryotes and eukaryotes. However, although the chemical reactions may not vary, the organization of the biosynthetic apparatus is very different. Vertebrates and yeasts possess type I fatty acid synthases (FASs) in which all of the enzymatic activities are encoded on one or two polypeptide chains, respectively. The acyl carrier protein (ACP) is an integral part of the complex. In contrast, in most bacterial and plant FASs (type II) each of the reactions are catalyzed by distinct monofunctional enzymes and the ACP is a discrete protein. Mycobacteria are unique in that they possess both type I and II FASs; the former is involved in basic fatty acid biosynthesis whereas the latter is involved in synthesis of complex cell envelope lipids such as mycolic acids. There therefore appears to be considerable potential for selective inhibition of the bacterial systems by broad-spectrum antibacterial agents (Jackowski, S. 1992. In Emerging Targets in Antibacterial and Antifungal Chemotherapy. Ed. J. Sutcliffc and N. Georgopapadakou. Chapman and Hall, New York; Jackowski, S. et al. (1989). J. Biol. Chem. 264, 7624-7629.)
The first step in the biosynthetic cycle is the condensation of malonyl-ACP with acetyl-CoA by FabH. In subsequent rounds malonyl-ACP is condensed with the growing-chain acyl-ACP (FabB and FabF, synthases I and II respectively). The second step in the elongation cycle is ketoester reduction by NADPH-dependent xcex2-ketoacyl-ACP reductase (FabG). Subsequent dehydration by xcex2-hydroxyacyl-ACP dehydrase (either FabA or FabZ) leads to trans-2-enoyl-ACP which is in turn converted to acyl-ACP by NADH-dependent enoyl-ACP reductase (FabI). Further rounds of this cycle, adding two carbon atoms per cycle, eventually lead to palmitoyl-ACP whereupon the cycle is stopped largely due to feedback inhibition of FabH and I by palmitoyl-ACP (Heath, et al, (1996), J.Biol.Chem. 271, 1833-1836). Fab H is therefore a major biosynthetic enzyme, which is also a key regulatory point in the overall synthetic pathway (Heath, R. J. and Rock, C. O. 1996. J.Biol.Chem. 271, 1833-1836; Heath, R. J. and Rock, C. O. 1996. J.Biol.Chem. 271, 10996-11000).
The antibiotic thiolactomycin has broad-spectrum antibacterial activity both in vivo and in vitro and has been shown to specifically inhibit all three condensing enzymes. It is non-toxic and does not inhibit mammalian FASs (Hayashi, T. et al.,1984. J. Antibiotics 37, 1456-1461; Miyakawa, S. et al., 1982. J. Antibiotics 35, 411-419; Nawata, Y et al., 1989. Acta Cryst. C45, 978-979; Noto, T. et al., 1982. J. Antibiotics 35, 401-410; Oishi, H. et al., 1982. J. Antibiotics 35, 391-396. Similarly, cerulenin is a potent inhibitor of FabB and F and is bactericidal but is toxic to eukaryotes because it competes for the fatty-acyl binding site common to both FAS types (D""Agnolo, G. et al.,1973. Biochim. Biophys. Acta. 326, 155-166). Extensive work with these inhibitors has proved that these enzymes are essential for viability. Little work has been carried out in Gram-positive bacteria
There is an unmet need for developing new classes of antibiotic compounds that are not subject to existing resistance mechanisms. No marketed antibiotics are targeted against fatty acid biosynthesis, therefore it is unlikely that novel antibiotics of this type would be rendered inactive by known antibiotic resistance mechanisms. Moreover, this is a potentially broad-spectrum target. Therefore, FabH inhibitors would serve to meet this unmet need.
This invention comprises novel compounds and pharmaceutical compositions containing these compounds and their use as PabH inhibitors that are useful as antibiotics for the treatment of Gram positive and Gram negative bacterial infections.
This invention further constitutes a method for treatment of a Gram negative or Gram positive bacterial infection in an animal, including humans, which comprises administering to an animal in need thereof, an effective amount of a compound of this invention.
The compounds of this invention are represented by Formula (I): 
wherein:
R represents OH, or NHSO2R2;
A represents NH or O;
B represents O, or NR1;
R1 represents Arxe2x80x2alkyl, or AlkylCO;
Ar and Arxe2x80x2 represent, independently, phenyl, thiophenyl, pyridinyl, or pyrimidinyl, all of which could be substituted with a substituting selected from the group consisting of: halo, including fluoro, bromo, chloro, iodo, NO2, CN, CO2R3, OR3, NR3R4, C1-10alkyl, C1-10alkoxy, aryloxy, arylalkoxy, and heteroaryloxy;
R2 represents alkyl, Arxe2x80x2alkyl, or Arxe2x80x2; and
R3 and R4 represent, independently, hydrogen, or C1-10alkyl.
Also included in the invention are pharmaceutically acceptable salt complexes.
As used herein, xe2x80x9calkylxe2x80x9d means both straight and branched chains of 1 to 6 carbon atoms, unless the chain length is otherwise limited, including, but not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl and the like. The alkyl may carry substituents such as hydroxy, carboxy, alkoxy, and the like.
The compounds of this invention may contain one or more asymmetric carbon atoms and may exist in racemic and optically active forms. All of these compounds and diastereomers are contemplated to be within the scope of the present invention.
Some of the compounds of this invention may be crystallised or recrystallised from solvents such as organic solvents. In such cases solvates may be formed. This invention includes within its scope stoichiometric solvates including hydrates as well as compounds containing variable amounts of water that may be produced by processes such as lyophilisation.
Since the antibiotic compounds of the invention are intended for use in pharmaceutical compositions it will readily be understood that they are each provided in substantially pure form, for example at least 60% pure, more suitably at least 75% pure and preferably at least 85%, especially at least 95% pure, particularly at least 98% pure (% are on a weight for weight basis). Impure preparations of the compounds may be used for preparing the more pure forms used in the pharmaceutical compositions; these less pure preparations of the compounds should contain at least 1%, more suitably at least 5% and preferably from 10 to 49% of a compound of the formula (I) or salt thereof.
Preferred compounds of the present invention include:
[4-(2,6-Dichloro-benzyloxy)-phenylamino]-2-phenyl-acetic acid;
[4-(2-Chloro-5-hydroxy-benzylamino)phenoxy]-2-phenyl-acetic acid;
[4-(2,6-Dichloro-benzylamino)-phenoxy]-2-phenyl-acetic acid;
[4-(2,5-Dichloro-benzylamino)-phenoxy]-2-phenyl-acetic acid;
{4-[3-(1,1-Difluoro-methoxy)-benzylamino]-phenoxy}-2-phenyl-acetic acid and (4-{Bis-[3-(1,1-difluoro-methoxy)-benzyl]-amino}-phenoxy)-2-phenyl-acetic acid;
{[4(6-Chloro-benzo[1,3]dioxol-5-ylmethyl)-amino]-phenoxy}-2-phenyl-acetic acid and {4-[Bis-(6-chloro-benzo[1,3]dioxol-5-ylmethyl)-amino]-phenoxy}-2-phenyl-acetic acid;
{4-[Acetyl-(2,6-dichloro-benzyl)-amino]-phenoxy}-2-phenyl-acetic acid;
4-{2-(4-[Acetyl-(2,6-dichloro-benzyl)-amino]-phenoxy}-2-phenyl-ethanoylsulfamoyl)-benzoic acid methyl ester; and
4-(2-{4-[Acetyl-(2,-dichloro-benzyl)-amino]-phenoxy}-2-phenyl-ethanoylsulfamoyl)-benzoic acid.
The present invention provides compounds of formula (I), 
wherein Rxe2x95x90OH, NHSO2Rxe2x80x3; Axe2x95x90NH, O; Bxe2x95x90O, NR1;
which can be prepared by reacting 4-nitrophenol with an aryl halide of Formula (2)
Arxe2x80x2CH2Xxe2x80x83xe2x80x83(2)
in presence of a base such as cesium carbonate in an appropriate solvent such as N,Nxe2x80x2-dimethylformate to afford a phenoxyether of Formula (3). 
Reduction of the nitro function in a compound of Formula (3) with an appropriate reducing agent such as tin (II) chloride in a solvent such as ethanol at a certain temperature gives an aniline of Formula (4). 
Reacting an aniline of Formula (4) with an alkyl xcex1-haloarylacetic acetate of Formula (5) 
provides an xcex1-aminoacetic acetate derivative of Formula (6). 
Hydrolysis of an ester of Formula (6) using a base such as lithium hydroxide in solvents such as tetrahydrofuran and water affords an acid of Formula (I), where Rxe2x95x90OH,Axe2x95x90NH,Bxe2x95x90O.
Reacting 4-amino-phenol with an alkyl xcex1-haloarylacetic acetate of Formula (5) provides an xcex1-phenoxyacetic acetate derivative of Formula (7). 
Alternatively, a compound of Formula (7) can be prepared by reacting 4-nitrophenol with a compound of Formula (5) followed by reducing the nitro group to the amino group under similar conditions described above.
Alkylation of an aniline derivative of Formula (7) with an aryl halide of Formula (2) in presence of a base such as cesium carbonate in an appropriate solvent such as N,Nxe2x80x2-dimethylformate to afford a mono- and/or a di-alkylated compound(s) of Formula (8) and/or (9). 
Hydrolysis of ester(s) of Formula (8) and/or (9) using a base such as lithium hydroxide in solvents such as tetrahydrofuran and water at certain temperature affords an acid of Formula (I), where Rxe2x95x90OH, Axe2x95x90O, Bxe2x95x90NR1, R1xe2x95x90H and/or Arxe2x80x2CH2.
Treatment of an aniline of Formula (I), where Rxe2x95x90OH, Axe2x95x90O, Bxe2x95x90NR1, R1xe2x95x90H, with acetic anhydride in presence of a base such as pyridine in a solvent such as dichloromethane gives an acylated compound of Formula (10). 
Coupling of an acid of Formula (10) with a sulfonamide of Formula (11)
R2SO2NH2xe2x80x83xe2x80x83(11)
using coupling reagents such as EDC and dimethylaminopyridine in an appropriate solvent such as dichloromethane affords an acyl sulfonamide of Formula (I), where Rxe2x95x90HNSO2R2, Axe2x95x90O, Bxe2x95x90NR1, R1xe2x95x90Ac. Any ester function in Rxe2x80x2 can be converted to an acid function using standard hydrolysis conditions described above.